Apparatus for detecting a vibratory movement of a laundry drum

ABSTRACT

An apparatus detects a vibratory movement of the rotary shaft of an internal unit, which is suspended such that it can vibrate, of a washing machine having a laundry drum which is driven by an electric motor. The apparatus has a sensor part and a measured-value detector which is connected to the rotary shaft and provides a measured variable which varies periodically with the rotational speed of the rotary shaft and periodically with the vibratory movement in at least one direction parallel to the axis of rotation or in at least one radial direction.

BACKGROUND OF THE INVENTION Field of the Invention

The invention relates to an apparatus for detecting a vibratory movementof the rotary shaft of an internal unit, which is suspended such that itcan vibrate, of a washing machine having a laundry drum which is drivenby an electric motor.

The internal unit of a washing machine or spin-dryer contains a washingcontainer, which has a laundry drum which is mounted in the containersuch that it can rotate, and a drive unit in the form of an electricmotor that usually drives the laundry drum via a reduction gear or atransmission. The internal unit is suspended in a machine housing suchthat it can vibrate and constitutes an overall system which can vibratein a damped manner and which is subject to unbalance-dependent resonancephenomena in specific regions of the rotational speed of the laundrydrum, this speed being lower than the rotational speed of the motor. Thecauses of the resonance phenomena are vibratory movements due tomomentary unbalances in the load in the laundry drum.

Vibratory movements such as these, which are the result of unbalances,can be countered in the program sequence of a washing machine orspin-dryer by a specific laundry distribution phase. For this purpose,the control program for driving the drum advances to a higher rotationalspeed for removing moisture and spin-drying the laundry in the laundrydrum only when, in the course of a laundry distribution phase of thistype, the unbalances have been compensated for or have been reduced atleast to a level which is suitable for introducing higher rotationalspeeds.

In order to detect such an unbalance in the laundry drum, German patentDE 37 41 791 C3 and European patent EP 0 349 789 B1 (corresponding toU.S. Pat. No. 5,098,224) disclose the use of a so-called tachogeneratoras a rotary encoder. This is connected to the motor shaft and produces asignal voltage which corresponds to the respective rotational speed ofthe laundry drum and whose frequency is proportional to the rotationalspeed. The signal provided by the tachogenerator thus virtuallyrepresents the actual rotational speed of the laundry drum, the speedfluctuating as a function of the unbalance of the laundry in the laundrydrum. A tachogenerator of this type as a rotary encoder thus detectsthose components of a vibratory movement of an internal unit, which issuspended such that it can vibrate, of a washing machine that lead to acorresponding angular acceleration or torque fluctuation about this axisof rotation.

SUMMARY OF THE INVENTION

It is accordingly an object of the invention to provide an apparatus fordetecting a vibratory movement of a laundry drum that overcomes theabove-mentioned disadvantages of the prior art devices of this generaltype.

With the foregoing and other objects in view there is provided, inaccordance with the invention, an apparatus for detecting a vibratorymovement of a rotary shaft of an internal unit of a washing machine. Thewashing machine has a laundry drum driven by an electric motor, and theinternal unit is suspended for allowing the internal unit to vibrate.The apparatus contains a sensor part and a measured-value detectorconnected to the rotary shaft and provides a measured variable varyingperiodically with a rotational speed of the rotary shaft andperiodically with the vibratory movement in at least one directionparallel to an axis of rotation of the rotary shaft or in at least oneradial direction.

For this purpose, provision is made first of a sensor part and second ofa measured-value detector which is also referred to below as an actuatorpart and is connected to the rotary shaft. The measured-value detectorand the sensor part provide a measured variable which variesperiodically with the rotational speed of the rotary shaft andperiodically with the vibratory movement in at least one direction (x,y, z), that is to say in the axial direction (x) and/or in a radialdirection (y, z). In this case, the actuator part and/or the sensor partcan expediently move axially or radially, for example are/is supportedsuch that they/it can move.

The invention is in this case based on the idea that a vibratorymovement of the rotary shaft and thus of the overall system or internalunit of a washing machine can be detected particularly reliably when, inaddition to a vibratory movement about the rotary shaft which isreflected in the directly detectable change in rotational speed, avibratory movement about at least one further axis is also detected,this axis not coinciding with the rotary shaft defined by the bearingshaft of the motor or of the laundry drum. Therefore, as is known, withan unbalanced load of laundry, the laundry drum rotates not only aboutthis axis of rotation which is defined by the bearing shaft of thelaundry drum, but, as a function of the position and the size of theunbalanced load, also follows vibratory movements in the or about theaxes which are orthogonal to the axis of rotation and represent the y-and z-axes based on a Cartesian coordinate system with the axis ofrotation on the x-axis.

In this case, the particularly critical vibratory movements about theaxes perpendicular to the bearing shaft or rotary shaft of the drum andalso pitching and yawing movements of the washing container or tub aredetected and thus identified. At an increased amplitude, the yawingmovements may therefore lead to the tub and thus the internal unit ofthe washing machine striking its side walls, while pitching movementsmay lead to the front face of the washing machine being struck.Accordingly, if at least one of these vibratory movements about the y-or z-axis, which runs orthogonal to the axis of rotation and thus to thex-axis, is separately or additionally detected, unbalances can becomparatively precisely determined and changes in the rotational speedcan be comparatively exactly controlled for reliable and effectiveoperation of the washing machine.

In one variant of the apparatus for detecting a vibratory movement ofthe rotary shaft of a laundry drum, the sensor part and themeasured-value detector are part of an acceleration sensor whosemeasured-value detector is expediently connected to the rotor of theelectric motor or to the drum bearing shaft. As a result, theacceleration sensor can assume the functions of a rotational-speedsensor or detector. Otherwise, at least some of the supply and/or signallines of the acceleration sensor are common lines of an existing rotaryencoder. This considerably reduces at least the cabling complexity.

In one advantageous refinement, the measured-value detector of theacceleration sensor is expediently sensitive in the axial direction orthe sensor part is expediently sensitive in the axial and/or radialdirection, and the measured-value detector and sensor part are formed insuch a way that they influence the rotary-encoder signal, which isproportional to the rotational speed or represents the rotational speed,by modulating the pulse width, the frequency or the amplitude. For thispurpose, the measured-value detector and/or the sensor part can moveaxially or radially with respect to the motor or drum-bearing shaft andthus with respect to the axis of rotation.

In addition, superimposition of the ability to move axially and radiallyand also an apparatus having two measured-value detectors or sensorparts, and sensor parts and measured-value detectors associated witheach of these and with the ability to move axially and/or radially inrelation to the axis of rotation, may be provided.

In one expedient embodiment, the acceleration sensor together with ameasured-value detector, which is borne such that it can move axiallyand whose ability to move is expediently limited by two stops, andtogether with a sensor part is in the form of a fixed-position forkedlight barrier. Instead of this optical embodiment, it is also possibleto detect changes in other physical variables that vibrate periodicallywith the laundry drum. Therefore, by way of example, a reflective,photoelectric, electromagnetic or piezoelectric embodiment of theacceleration sensor may be provided.

The common basic principle of these is that the ratio of an expedientlytoothed or perforated division that is predefined by the measured-valuedetector changes as a result of a vibratory movement. For example, in anembodiment having two stops, a different division ratio is thereforeproduced at each of these stops on account of an axial or radialmovement, resulting from a vibratory movement, of the measured-valuedetector or of a part thereof in relation to the fixed-position sensorpart. These changes in the division ratio vary periodically with thevibratory movement of the washing tub. In the case of an in particulardigitally regulated or controlled washing-machine drive, this is in turnreflected in a change in the mark/space ratio and therefore in the clockrate of the rotational-speed or rotary-encoder signal which is generatedduring detection of the rotational speed.

Other features which are considered as characteristic for the inventionare set forth in the appended claims.

Although the invention is illustrated and described herein as embodiedin an apparatus for detecting a vibratory movement of a laundry drum, itis nevertheless not intended to be limited to the details shown, sincevarious modifications and structural changes may be made therein withoutdeparting from the spirit of the invention and within the scope andrange of equivalents of the claims.

The construction and method of operation of the invention, however,together with additional objects and advantages thereof will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic, plan view of a washing machine having aninternal unit which is suspended such that it can vibrate, an electricmotor which drives a laundry drum, and an apparatus for detectingvibratory movements and disposed on the electric motor;

FIG. 2 is a diagrammatic, sectional view of the detection apparatus witha measured-value detector and a fixed-position sensor part;

FIGS. 3A and 3B are diagrammatic, sectional views of detail III fromFIG. 2 on an enlarged scale with a toothed and, respectively, perforatedactuator ring;

FIG. 4 is a sectional view through the measured-value detector of thedetection apparatus taken along the line IV-IV shown in FIG. 2;

FIG. 5 is a diagrammatic, plan end view of the measured-value detectoraccording to FIG. 2 with two mutually orthogonal sensor parts;

FIG. 6 is a detailed, sectional view of the measured-value detectoraccording to FIG. 5 in an illustration as shown in FIGS. 3A and 3B;

FIG. 7 is a diagrammatic, sectional view of a first embodiment of aradially moving sensor part in an illustration as shown in FIG. 5; and

FIG. 8 is a diagrammatic, plan view of a second embodiment of theradially moving sensor part in an illustration as shown in FIG. 6.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In all the figures of the drawing, sub-features and integral parts thatcorrespond to one another bear the same reference symbol in each case.Referring now to the figures of the drawing in detail and first,particularly, to FIG. 1 thereof, there is shown a schematic view, froman end and towards the rear face (which is opposite a loading opening)of a machine housing 1, of an internal unit 2, also referred to as anoverall system below, of a washing machine or of a spin-dryer. Theinternal unit 2 is suspended in the machine housing 1 by springs 3 andfriction dampers 4 such that it can vibrate. The internal unit 2contains a washing tub 5, which is suspended such that it can thereforevibrate and is elastically damped, and a washing or laundry drum 6,which is mounted in particular in the rear wall of the washing tub 5such that it can rotate, and also an electric motor 7 that drives thedrum 6. A bearing shaft of the electric motor or motor shaft 8, alsoreferred to as rotary shaft below, runs at least approximately parallelto a drum shaft or bearing shaft and thus to a rotary shaft 9 of thelaundry drum 6, the rotary shafts 8, 9 running in the x-direction withrespect to the illustrated Cartesian coordinate system.

In the exemplary embodiment, an apparatus for detecting vibratorymovements, referred to below as an acceleration sensor 10 and in whichthe functions of a rotational-speed sensor are expediently alsointegrated or implicit, is provided on the rotary or bearing shaft 8 ofthe electric motor 7. As an alternative, the acceleration sensor 10 canalso be disposed analogously in the region of the rotary shaft 9 of thelaundry drum 6. In this case, the, for example electronic, accelerationsensor 10 can be fitted at any defined angle relative to a top surfaceof the washing machine, irrespective of the inclination of the laundrydrum 6 which, for example, may be inclined by up to 15° with respect tothe horizontal.

A rotary-encoder or sensor signal S_(I), which is provided by theacceleration sensor 10 and expediently also represents the rotationalspeed of the motor or drum, can be supplied to an evaluation or controldevice 11. Further measured variables and/or control variables, inparticular a rotational-speed setpoint value S_(S), can in turn besupplied to the evaluation or control device 11. The device 11 can, forits part, output a control variable or a control signal S_(D) to theelectric motor 7 in order to set or control the rotational speed. Whenthe laundry drum 6 is not rotating, the sensor signal S_(I) or thechange in it can also be used to detect the degree of loading in thedrum, since the sensor or quiescent signal from the acceleration sensor10 changes as the laundry drum 6 is filled.

According to FIGS. 2 to 4, the acceleration sensor 10 contains ameasured-value detector 12, also referred to below as an actuator, and asensor part 13. The sensor part 13 is fixed in position in relation tothe measured-value detector 12 and, in this case, can be mounted on afixed part of the electric motor 7. The sensor part 13 can also move ina tangential direction (y, z)—in the z-direction here. This is expedientin particular in the case of a motor configuration without a separatetachogenerator and with a motor 7 without any sensors and in which theactual rotational-speed information is obtained from the motor currentand, if appropriate, the sensor is used for deflection on a furtheraxis.

The sensor part 13, which is in the form of a forked light barrier inthe present case, surrounds an actuator ring 14 of a first actuator part15 of the measured-value detector 12 by the limbs of the fork lightbarrier. The first actuator part 15 coaxially surrounds a secondactuator part 16, which is connected to the drive or bearing shaft 8 ofthe electric motor 7 and thus to the rotary shaft such that it is fixedin terms of rotation, and can move with respect to the second actuatorpart parallel to the axis of rotation 8, 9.

In order that the moving first actuator part 15 can move along the axisof rotation 8, 9 in the x-direction with as little friction as possibleon the (second) actuator part 16 which is fixed in terms of rotation,the two actuator parts 15, 16 are connected using balls 19 which run ingrooves 17 and 18. In this case, the length of the groove 17 formed inthe moving actuator part 15 is expediently greater than the length ofthe groove 18 formed in the actuator part 16 that is fixed in terms ofrotation.

In particular, the length of the groove 17 formed in the moving actuatorpart 15 is greater than or equal to the sum of two end spacing gaps 20,21 between the two actuator parts 15 and 16. At least two grooves 17, 18filled with balls 19 are preferably disposed, in particularsymmetrically, about the center of the axis of rotation 8, 9. The balls19 also indirectly increase the inert mass of the moving actuator part15 since the balls assume its direction of movement (x-direction) duringacceleration and effectively push the moving actuator part 15, if thegroove 17 in the moving actuator part 15 is smaller than thecorresponding groove 18 in the fixed actuator part 16.

The actuator ring 14 that extends in the axial direction (x-direction)is integrally formed on the end of the moving actuator part 15.According to FIG. 3A, the actuator ring 14 can be formed withsawtooth-like teeth as a toothed profile 22 which can taper from thebase of the ring to the free end of the tooth. As an alternative, theactuator ring 14 according to FIG. 3B can also be formed with holecutouts as a perforated profile 23. The essential feature when formingthe actuator ring 14 is that one profile side 22 a, 23A is made to bevariable while the other profile side 22 b or, respectively, 23B runsparallel to the axis of rotation 8, 9 so that a sawtooth profile, forexample, is created overall. This shaping of the actuator ring 14 fixesthe timing of a signal transition of the acceleration sensor 10irrespective of the position of the moving actuator part 15.

The forked light barrier as the sensor part 13 protrudes beyond theactuator ring 14, the opening width of the forked light barrier beingwider than the thickness of the actuator ring 14 and its opening depthbeing greater than the sum of the two spacings or spacing gaps 20 and21. In this case, the forked light barrier 13 is disposed in such a waythat its active components likewise centrally illuminate the actuatorring 14 in the center position of the moving actuator part 15. Theillustrated parts of the acceleration sensor 10 can at least partiallybe surrounded by a housing (in a manner not shown in any more detail) inorder to protect the actuator or measured-value detector 12 and thesensor part 13 from contamination.

During operation of the washing machine, both the actuator part 16 whichis fixed in terms of rotation and also, by the balls 19 acting asdrivers, the rotating actuator part 15 rotate when the electric motor 7is running. The beam path of the forked light barrier 13 is in this caseperiodically interrupted by the toothed profile 22 (FIG. 3A) or the ringwebs 25 (FIG. 3B) of the perforated profile 23 which are present betweenthe hole cutouts 24. The rotational speed_(act) of the motor 7 isobtained from the light and dark changes detected at the forked lightbarrier 13 per unit time divided by the number of ring teeth 26 or holecutouts 24 on the circumference of the actuator ring 14 which causethese light and dark changes.

If the motor 7, which is itself fixedly connected to the washing tub 5,now accelerates in the axial direction (x-direction) on account ofnon-uniform loading of the laundry drum 6, the moving actuator part 15of the acceleration sensor 10 will follow this movement between stops 27a and 27 b shown in FIG. 2 until the maximum speed is reached in theaxial, or x-, direction. The axial movement of the motor 7 and of theoverall system 2 is at least approximately sinusoidal if the deflectionof the internal unit 2 and thus of the overall system is smaller thanits free spacing from the housing parts of the machine housing 1. Inthis case, the period of this harmonic vibration corresponds to therotational speed_(act) of the drum.

At the points at which the motor 7 or the overall system 2 reaches itshighest axial speed, and from which the motor or overall system is againdecelerated to the reversal points, the moving actuator part 15 willmaintain the instantaneous or current direction of movement and passthrough the spacing gaps 21, 22, continuing at the maximum speed. As aresult, the beam path of the forked light barrier 13 moves into theillustrated regions a and b in the toothed profile 22 as shown in FIG.3A. In an analogous manner, the beam path of the forked light barrier 13moves into the illustrated regions a′ and b′ in the perforated profile23 as shown in FIG. 3B. At a constant rotational speed_(act) of themotor 7 and, respectively, of the rotary shaft 8, 9 and thus with aconstant number of light/dark changes, these shifts in region cause achange in the time periods in which the beam path of the forked lightbarrier 13 is interrupted or is not interrupted by the profiles 22 and23 and thus becomes dark or light.

In the case of an electrical output or sensor signal S_(I) measured atthe forked light barrier 13, the mark/space ratio changes at a constantfrequency. Forming the actuator ring 14 as a sawtooth profile 22, 23results in that, depending on the direction of rotation about the axisof rotation 8, 9, one of the two profiled edges 22 b, 23B will remainconstant while the other profiled edge 22 a, 23A changes in relation tothe movement of the moving actuator part 15. It is therefore possible tomeasure by electrical measures whether and, if appropriate, at whichstop 27 a, 27 b the moving actuator part 15 is currently present and inwhich direction parallel to the axis of rotation 8, 9 the laundry drum6, together with the washing tub 5, is currently moving.

Constant timing or time detection therefore provides information aboutthat point in time at which the moving actuator part 15 was last at oneof the two stops 27 a or 27 b. The moving actuator part 15 will providea constantly changing mark/space ratio at the forked light barrier 13 aslong as it has not reached the opposite stop 27 b or, respectively, 27a. Upon reaching the opposite stop 27 b or 27 a, the detected mark/spaceratio becomes constant again. At this point, the time is recorded ordetected for a second time. The difference between the two times or timeintervals measured or detected here, together with the distance or thetravel between the two stops 27 a and 27 b, give the maximum speed ofthe moving actuator part 15. This speed is identical to the maximumspeed of the motor 7 and of the overall system or internal unit 2 in theaxial or x-direction. The deflection of the overall system or internalunit 2 can be determined or calculated from this using the rotationalspeed_(act) of the drum.

The important factors here are the deflections or vibratory movements inthe axial direction (x-direction) of the internal unit 2 which issuspended by the springs 3, is damped by the friction dampers 4 and hasthe washing container 5, the laundry drum 6 and also the motor 7. Thisis true in particular close to or in the resonance region, where severedeflections or vibratory movements may lead to mechanical destruction.At comparatively high or relatively high rotational speeds_(act), anunbalanced overall system causes vibration which, although no longerleading to the internal unit 2 striking the machine housing 1, ishowever just as undesirable. For a rotational speed_(act) in the regionabove resonance, the apparatus according to the invention thereforeprovides for the rotating actuator part 15 to be fixed with respect tothe actuator part 16 which is fixed in terms of rotation. This can takeplace, in particular, in the manner of a centrifugal brake whichincreases the friction between the two parts 15, 16 as a function of therotational speed until they are completely fixed. In this case, in onerefinement of the actuator or measured-value detector 12 and in a mannernot shown in any more detail, the moving actuator part 15 may have agroove in the radial direction, in which groove the centrifugal brakelatches and thus holds the moving actuator part 15 in a defined centralposition.

In one variant of the apparatus according to the invention that is notshown in any more detail, the moving actuator part 15 is not fixedlyconnected to the actuator part 16 that is fixed in terms of rotation.Instead, the moving actuator part 15 can be located on a fixed motorpart such that it can move with the forked barrier and thus with thefixed-position sensor part 13. This may be advantageous forinstallation, in particular to compensation for manufacturingtolerances.

In one expedient development, in addition to the actuator ring 14,extending in the axial direction (x-direction), for detecting thepitching movement on the moving actuator part 15, according to FIGS. 5and 6, a further actuator ring or collar 28, extending in a radialdirection (y- and/or z-direction), can be provided on the actuator ormeasured-value detector 12. The further actuator ring or collar is usedto detect the so-called yawing movement, that is to say a rotarymovement of the overall system or internal unit 2 about an imaginaryvertical through its centre point, and thus a movement in thez-direction illustrated in FIG. 6.

The actuator collar 28 which is likewise expediently toothed orperforated has an associated further forked light barrier 29 as sensorpart. In this embodiment, the second forked light barrier 29 is locatedon a moving part that can move in the radial direction. In thisembodiment too, the mark/space ratio of an electrical signal S_(I)measured at the second forked light barrier 29 changes analogously as afunction of the yawing movement. It should be taken into account herethat, in the case of combined measurement of the pitching and yawingmovements, the opening width of the second forked light barrier 29 alsohas to record the movement of the actuator collar 14 which moves in theaxial direction.

In the embodiment according to FIGS. 7 and 8, the sensor part or theforked light barrier 13 is not fixed in position but is mounted suchthat it can move in the radial direction y. For this purpose, the sensorpart 13 is attached to a holding apparatus 30 that, for its part, isheld on the motor housing for example. To this end, the holdingapparatus 30 is composed of the light barrier or the sensor part 13, aholding arm or a holder 31, and a counterweight 32, the holdingapparatus being mounted at a bearing point 33. The bearing is the resultof two different variants.

Therefore, in a first variant, the light barrier 13 is fixed in thex-direction. If the actuator part 15 moves in the x-direction, themark/space ratio and therefore the light and dark periods at the lightbarrier 13 change. When the holder or holding apparatus 30 moves in they-direction, that is to say in the direction perpendicular to the planeof the drawing of FIG. 7, the frequency of the light and dark changesvaries in such a way that the measured frequency is lower when themoving actuator part 15 is rotated in the clockwise direction and theholding apparatus 30 moves out of the plane of the drawing—that is tosay with the same direction of rotation as the moving actuator part15—and the measured frequency is higher with the opposite direction ofrotation. The holding apparatus 30 thus oscillates about an (imaginary)extension of the center of the motor shaft.

In a second variant, the actuator part 15 is fixedly connected to theactuator part 16 that is fixed in terms of rotation. In this case, theholder 30 and the light barrier 13, together with the counterweight 32,have to produce both movements in the x- and in the y-direction. In thiscase, the functional principle remains the same, while the holder 30 nowhas to move with only two degrees of freedom. The bearing or the bearingpoint 33 should therefore effectively be in the form of ball bearings.

If the washing container or tub 5 of the washing machine now acceleratesin a radial direction y and/or z, the light barrier 13 which is mountedsuch that it can move rotates in or counter to the respective directionof rotation of the washing container 5. The rotary movement of the motor7 generates a square-wave signal, which is proportional to therotational speed, at the light barrier 13 on account of the beam pathbeing interrupted. The frequency, that is to say the mark/space ratio ofthe square-wave signal resulting from the light/dark changes, decreasesor increases when the moving light barrier 13 is deflected in or counterto the current direction of rotation.

According to the illustration shown in FIG. 8, the pendulum weight orcounterweight 32 is formed by the light barrier 13 itself. In thisembodiment too, two stops 34 limit the deflection of the radialmovement. In this case, the illustrated stops 34 cannot be overcome byan oscillating light barrier 13 and/or an oscillating holding apparatus30. The acceleration and therefore the deflection of the washingcontainer 5—in the radial direction y here—can in turn be determinedfrom the duration of the frequency change.

This application claims the priority, under 35 U.S.C. § 119, of Germanpatent application No. 10 2004 029 625.1, filed Jun. 18, 2004 and Germanpatent application No. 10 2004 053 216.8, filed Nov. 4, 2004 the entiredisclosure of the prior application is herewith incorporated byreference.

1. An apparatus for detecting a vibratory movement of a rotary shaft ofan internal unit of a washing machine, the washing machine having alaundry drum driven by an electric motor, the internal unit beingsuspended for allowing the internal unit to vibrate, the apparatuscomprising: a sensor part; and a measured-value detector connected tothe rotary shaft and providing a measured variable varying periodicallywith a rotational speed of the rotary shaft and periodically with thevibratory movement in at least one direction parallel to an axis ofrotation of the rotary shaft or in at least one radial direction.
 2. Theapparatus according to claim 1, further comprising an accelerationsensor, said sensor part and said measured-value detector are parts ofsaid acceleration sensor.
 3. The apparatus according to claim 1, whereinsaid measured-value detector is connected to a rotor of the electricmotor or to a drum-bearing shaft.
 4. The apparatus according to claim 1,wherein said measured-value detector influences a rotary-encoder signal,which represents the rotational speed of the electric motor or thelaundry drum, by modulating a pulse width, a frequency or an amplitude.5. The apparatus according to claim 1, wherein said measured-valuedetector has an actuator part which is fixed in terms of rotation withrespect to the axis of rotation.
 6. The apparatus according to claim 5,wherein said measured-value detector has an actuator part which can moveaxially and/or radially with respect to the axis of rotation.
 7. Theapparatus according to claim 6, wherein said actuator part which isfixed in terms of rotation and said actuator part which can move arecoupled to one another such that they can rotate.
 8. The apparatusaccording to claim 4, further comprising two stops, said measured-valuedetector is mounted such that it can move and whose ability to move islimited by said two stops.
 9. The apparatus according to claim 8,wherein said measured-value detector is formed in such a way that aratio of a division predefined by said measured-value detector changesas a result of the vibratory movement.
 10. The apparatus according toclaim 9, wherein said measured-value detector has a device with atoothed or perforated division.
 11. The apparatus according to claim 9,wherein said measured-value detector is formed in such a way that adifferent division ratio is produced at each of said two stops, beingmutually opposite stops, on account of an axial or radial movement,resulting from a vibratory movement, of said measured-value detector orof a part thereof in relation to said sensor part being a fixed positionsensor part.
 12. The apparatus according to claim 11, wherein changes inthe division ratio vary periodically with the vibratory movement. 13.The apparatus according to claim 12, wherein a periodic change in thedivision ratio in the electric motor is included in a change in amark/space ratio of the rotary-encoder signal generated during detectionof the rotational speed.
 14. The apparatus according to claim 1, whereinat least one of said measured-value detector and said sensor part isintegrated in a rotational-speed sensor that is connected to the rotaryshaft.
 15. The apparatus according to claim 1, wherein said sensor partis a forked light barrier.
 16. The apparatus according to claim 1,wherein said sensor part can move axially and/or radially with respectto the axis of rotation.
 17. The apparatus according to claim l, whereinsaid sensor part can move radially and said measured-value detector or apart thereof can move axially with respect to the axis of rotation. 18.The apparatus according to claim 1, wherein said sensor part can moveaxially and said measured-value detector or a part thereof can moveradially with respect to the axis of rotation.
 19. The apparatusaccording to claim 16, wherein said measured-value detector has twomutually opposite stops, said sensor part produces a different divisionratio at each of said mutually opposite stops on account of an axialand/or radial movement, resulting from a vibratory movement.